As described in FIG. 1, a 3GPP network or a Wifi network is combined by more than one Tracking Area (TA), and User Endpoint (UE), which register in an area including one TA or more than one TA (TA list). Usually, the UE receives and saves the TA or TAs sent from an area that the UE has registered. For example, the UE receives TA1 sent from area1 and saves it in its TA list when the UE is moving into area1. If later the UE moves into area2, it receives TA2 sent from area2 and adds TA2 into its TA list or replaces TA1 with TA2. When the UE moves into a new TA, a Tracking Area Update (TAU) procedure will be initiated.
In a conventional network, as described in FIG. 2, most of the areas are covered by the same radio technologies, e.g. a Long Term Evolution (LTE) network or other 3GPP network, and a default mobility policy can be applied. Only in some narrow area which is covered by different radio technologies, e.g. an LTE network and Wifi network, and a special mobility policy shall be applied. The mobility policies include:
1) Inter system mobility policy including a set of operator-defined rules and preferences that affect the inter-system mobility decisions taken by the UE; and
2) Access network discovery information including a list of access networks available in the vicinity of the UE for all the access technology types requested by the UE.
In the 6 TAs (TA1˜TA6) of FIG. 2, different mobility policies are applied:
TA4: outside of the Wifi area, the LTE network is selected.
TA2, 3, 6: inside the Wifi area, the WiFi network is selected.
TA1: almost outside of the Wifi area, the LTE network is selected.
TA5: part of the TA is inside of the Wifi area, the network selection is based on more accurate location information.
When the UE is moving between TAs covered by different networks, the mobility policy will be updated. A special TA is the TA or a TA List at which the mobility policy will be updated if the UE is moving into the special TA. A non-special TA is the TA or TA List at which the mobility policy will not be updated if the UE is moving into the non-special TA. In FIG. 2, the TA or TA List which overlapped overlay by different radio technologies are the special TAs. So TA2, TA3, TA5 and TA6 are the special TAs when UE is located in TA1; TA1, TA4 and TA5 are the special TAs when UE is located in TA2.
In the 3GPP network, as described in FIG. 3, when the UE is moving between the TAs, the mobility management is implemented by an MME (Mobility Management Entity) via tracking the UE's location or the TA. MME functions include Tracking Area list management. All the tracking areas in a Tracking Area List to which a UE is registered are served by the same serving MME. Tracking Area list management comprises the functions to allocate and reallocate a Tracking Area Identity list to the UE. Moreover, the Network Discovery and Selection is implemented by an ANDSF (Access Network Discovery and Selection Function). The ANDSF contains data management and control functionality necessary to provide network discovery and selection assistance data as per operators' policy. The ANDSF is able to initiate data transfer to the UE, based on network triggers, and respond to requests from the UE. The ANDSF stores the network topology information and shall send available access network(s) and the mobility policies to the UE in response to the UE's request or based on the network triggers.
The 3GPP has described a mechanism of Network Discovery and Selection by sending the mobility policies from the ANDSF to the UE (see 3GPP TS 23.402 and TS 24.302). As described in 3GPP, there are two methods, push model and pull model, for ANDSF to send the policies to the UE.
In the push model the ANDSF may update the inter-system mobility policy based on network triggers. To provide the UE more useful and precise information, the ANDSF shall be able to limit the information provided to the UE, which is based on the UE's current location, UE capabilities, etc.
In the pull model of communication, the UE sends a query to the ANDSF to retrieve information about available access networks in its vicinity. The UE may include the following information in the request: 1) UE's current location; and 2) UE capabilities (e.g. a list of access networks that can be selected).
But the 3GPP did not describe detail mechanism which is necessary to Network Discovery and Selection:
In push model, how the ANDSF gets the network triggers to update the inter-system mobility policy, and how the ANDSF gets the UE's current location for limiting the information provided to UE are not described.
In pull model, when the UE sends query to the ANDSF is not described.
Therefore, in current 3GPP specification, there is no mechanism to update the mobility policies to the UE when the UE is moving to a new area.